Sams Teach Yourself SQL in 10 Minutes

Combining Aggregate Functions

All the examples of aggregate function used thus far have involved a single function. But actually, SELECT statements may contain as few or as many aggregate functions as needed. Look at this example:

SELECT COUNT(*) AS num_items,
       MIN(prod_price) AS price_min,
       MAX(prod_price) AS price_max,
       AVG(prod_price) AS price_avg
FROM Products;

num_items   price_min         price_max        price_avg
----------  ---------------  ---------------  ---------
7            3.4900            11.9900          6.0614

Here a single SELECT statement performs four aggregate calculations in one step and returns four values (the number of items in the Products table, and the highest, lowest, and average product prices).

Caution

Naming Aliases When specifying alias names to contain ...